Genotypes of Candida albicans involved in development of candidiasis and their distribution in oral cavity of non-candidiasis individuals.

Genotype characteristics and distribution of commensal Candida albicans should be studied to predict the development of candidiasis, however, extensive genotype analysis of commensal C. albicans has not been made. In this study, 508 C. albicans isolates were collected from patients with/without candidiasis and divided into 4 isolate groups (SG-1, oral cavity of non-candidiasis patients; SG-2, patients with cutaneous candidiasis; SG-3, patients with vaginal candidiasis; SG-4, patients with candidemia). These isolates were characterized to study the relationship between genotypes and pathogenicity using microsatellite analysis. Using CDC3 and CAI, 5 genotypes (I, 111: 115/33: 41; II, 115: 119/23: 23; III, 115: 123/18: 27; IV, 115: 123/33: 40; and V, 123: 127/32: 41) were found in 4.2%, 8.9%, 7.1%, 2.2% and 3.1% of the isolates, respectively. Genotypes II and III were commonly found in all isolate groups. These genotypes were further divided into 28 types by additional HIS3 and CAIII microsatellite markers. In this analysis, C. albicans with type 6 and type 23 was widely distributed as a commensal species in the oral cavity of non-candidiasis patients and found to be related with candidiasis development. Additionally, genotypes I and IV were found in SG-2 and/or SG-4, suggesting that the fungus with those genotypes is also involved in this development. In contrast, genotype V was not identified in any infective isolates.

Microsatellite-based genotyping of Candida albicans isolated from patients with superficial candidiasis.

This study aimed to examine the genotype distribution of Candida albicans and the major genotypes involved in superficial candidiasis. The genotypes of C. albicans isolated from the infection sites of patients with superficial candidiasis (referred to as infection isolates) were analyzed by fragment analysis using 4 microsatellite markers (HIS3, CDC3, CAI and CAIII). Genotypes of the infection isolates were compared with those of C. albicans isolated from oral mucosa of non-candidiasis patients (referred to as oral isolates). Isolates of C. albicans showed 4 major genotypes for HIS3/CAI (" a " for 148 : 148 / 23 : 23," b " for 148 : 160 / 33 : 41," c " for 148 : 164 / 32 : 41 and " d " for 152 : 152 / 18 : 27). The genotypes " a "," b " and " d " were commonly found in oral (4.7, 8.8 and 7.6%, respectively) and infection (6.6, 9.2 and 15.4%, respectively) isolates. No isolates of genotype " c " were isolated from infection sites. The genotype " a " was found in the isolates from patients with genitalia candidiasis. Genotyping of multiple isolates from an individual patient showed that C. albicans from infection sites was genetically homogenous as compared with that of oral isolates, even in the same patient with candidiasis.

Genotyping of Candida albicans by fragment analysis of microsatellites combined with 25S rDNA and RPS-based strategies.

Because of its high discriminatory potential, fragment analysis of microsatellites has been frequently used for genotyping of Candida albicans at the strain level. In order to evaluate a genotyping system based on the fragment analysis of microsatellites combined with PCRs targeting 25S rDNA and RPS, 456 independent strains of C. albicans were subjected to genotype analysis using 4 microsatellite markers (CDC3, HIS3, CA I and CA III), followed by 25S rDNA and RPS-based genotyping. The fragment analysis using CA I showed the highest discriminatory potential (DP=0.9782), followed by HIS3 (DP=0.8780). Using combined microsatellite markers, 456 C. albicans strains were divided into 384 genotypes (DP=0.9984). PCRs targeting 25S rDNA and RPS were performed to differentiate the strains that showed identical genotypes in the fragment analysis, resulting in 434 genotypes (DP=0.9996). The combined genotyping system showed high discriminatory power at the strain level, and therefore is useful for rapid genotyping in molecular epidemiological studies of candidiasis.

Improvement of the repetitive sequence-based identification and genotyping of Candida albicans using ALT-specific primers.

The nucleotide sequences of the inner repeats of the repetitive sequence (RPS), termed ALTs, of Candida albicans and its related species C. albicans var. stellatoidea and C. dubliniensis, were analyzed. ALT sequences were grouped into 4 types for C. albicans (Aa, Ab, Ac and Ad) and C. albicans var. stellatoidea (Sa1, Sa2, Sb, Sc and Sd), and 3 types for C. dubliniensis (Da, Db and Dc). In addition to the primer set P-II (specific to RPS), 2 primer sets (AS-I and AiR-I) specific to the nucleotide sequences of C. albicans ALT were designed and tested for their potential for RPS-based identification/genotyping of C. albicans. PCRs using AS-I and AiR-I clearly distinguished C. albicans from both C. albicans var. stellatoidea and C. dubliniensis. Furthermore, the strains of C. albicans that showed similar electrophoretic patterns in the PCR using P-II were discriminated at the subtype level. These results indicate that the PCRs using RPS- and ALT-specific primer sets are useful as simple and rapid systems for the specific identification and genotyping of C. albicans.